[TenTec] My Two Cents - Units

[Paul Littleton]

I was trained as a mechanical engineer in the late '70's. At that time the United States was supposed to convert to SI as a system of units. Just before my senior year, my schooled realized that the U.S. wasn't going to convert after all and I spent a fair amount of effort learning the existing system of units. As a result I was forced to deal with both systems.

Most people, in this country, learn to loath the "metric" system because they are taught conversion factors between "English" and "metric" systems until they go insane. If so,done is immersed in SI, it is really a rather nice system to deal with.

 I make a point to separate "metric" from SI, because there are a number of metric systems and one SI system. Hertz is in SI and cycles/second exists in the other metric systems, as well as the English system. Hertz is just a name given to cycles/second to honor a German physicist In the SI system of measurement. No big deal, just a name. There is really no conversion involved. One Hertz equals one cycle/second.

I think the problem that may have started this discussion is the prefix used to move the decimal point around. An interesting note is that the same set of prefixes is used for both SI and the English systems. One kilohertz equals one kilocycle/second. One megahertz equal one megacycle/second.

 Another possible point of conversion is what I call the "lazy" use of units. Frequency cannot be specified in cycles or kilocycles. The time unit needs to be included. 

Best Regards,
Paul

tapped out on an iPad